Air handling systems, such as heating, ventilation, and air conditioning (HVAC) systems, are an important feature of modern building infrastructure. It is often critical that air which flows though air handling systems be continuously monitored for the presence of impurities that may pose a threat to the health and well-being of a building's occupants. For example, it is common to monitor the levels of oxygen, carbon monoxide, particulate, and smoke in air that flows through a building's air handling system. Such monitoring is typically facilitated by duct detectors that are installed at various locations throughout a building's ductwork.
Unlike conventional smoke detectors and other so-called “point detectors” that are commonly mounted to ceilings or walls to passively sense convection currents of ambient gas, a duct detector is encased in a sealed housing mounted to the exterior of a duct. An inlet conduit is in fluid communication with the interior of the detector housing and extends into the duct to gather air from therein. The gathered air flows into the detector housing, through the duct detector, and back into the duct through an exhaust conduit. The duct detector is thereby able to continuously sample and analyze the large volumes of air that flow through the duct. If certain properties of the sampled air exceed or fall below predetermined limits, the duct detector can be configured to actuate an alarm and/or deactivate blowers that drive air through the air handling system to mitigate the further spread of unsuitable air.
It is known that performance of duct detectors can degrade over time due to reasons such as electrical failure or particulate clogging of a detector's filter screen. Governmental agencies may therefore require that duct detectors be periodically tested to demonstrate proper functionality. Such testing is typically performed by a technician or other individual who manually introduces smoke or particulate into an air handling system, such as from a spray canister, at a location immediately upstream from the duct detector. The smoke or particulate flows into the duct detector and causes the detector to enter an alarm mode if the detector is functioning properly.
A problem commonly associated with testing the functionality of duct detectors in the manner described above is that duct detectors are often installed in elevated locations, sometimes above ceilings, with few surrounding structures capable of supporting the weight of an individual during testing. Detectors that are located in such areas offer poor accessibility, rendering the task of functional testing highly inconvenient and even hazardous. As a result, testing is sometimes not performed as frequently as it should be and, in some cases, is entirely forgone.